Site description The Jasons are a group of remote islands, to the far
north-west of West Falkland. Some are scenically spectacular,
with cliffs and craggy peaks, while others are low lying and
covered with Tussac.
Steeple Jason is a large island, 5 miles (8 km) long, running
south-east to north-west with an average width of around
0.6 miles (1 km). The island is divided into two main
sections by a narrow neck, which marks the only break in a
ridge of hills with steep slopes on both sides. The island
peaks at 263 m towards the north and again at 290 m
towards the south. At the northern point a wide, low plateau
forms an important area for breeding colonial seabirds,
which extend, in more scattered colonies, along the southern
steep coastlines. The main stands of Tussac are along the
southern shorelines and extend from around 30 m to the
highest points of the island. Scattered patches of Tussac also
exist in the centre of the island and there is a large stand in
the middle of the northern half on the eastern coast.
Grand Jason is the largest of the group and has a similar
history of stocking to Steeple Jason. The terrain varies from
steep cliffs and high plateaux with gullies to Tussac-covered
west-facing and south-facing slopes. There are severely
eroded areas of ‘black ground’, particularly at the northern,
south-eastern and western extremities. The island’s peak is
at 361 m and Tussac is sparse above 60–90 m, with low
grasses and small cushion plants.
Steeple Islet is a small island, generally low lying, with
boulder beaches and low cliffs, sloping towards a rocky
north-western point. Almost the entire island is covered in
dense Tussac grass, which has apparently never been grazed.
Flat Jason is a low-lying Tussac island with vertically
dipping rock strata, and is possibly the largest island in the
Falklands archipelago that has not been grazed, partly due
to the difficulties of access. The island is almost 3.7 miles (6
km) long on a north-west to south-east axis, with an average
width of some 600 m. At the centre of the island there is a
narrow neck with a boulder beach that may sometimes be
tidally inundated. The northern coasts are mainly boulder
beaches with rocky outcrops, while the southern shores are
more formidable, with steep-sided mini stacks and cliffs.
Elephant Jason has a long ridge rising to a height of 208 m,
sloping into low-lying plateaux thickly covered with dense
Tussac on the northern and eastern coasts, and with sheer
cliffs on the western coast. The fringe of Tussac extends
around most of the island, giving way at the northernmost
point to areas of grass and heath. For a short time early in
the 20th century Elephant Jason was used as a base for
government sealing inspectors, who constructed a shanty on
the island. The remains of the cast iron stove can still be
seen.
South Jason is a long, narrow island, running almost due
east–west and reaching over 4.3 miles (7 km) in length and
only 0.6 miles (1 km) wide at its widest point. The entire
island has a central ridge reaching around 300 m in height,
flattening out to the east and west. The eastern point has a
dense cover of Tussac, while the western point is drier, with
sparse grassland and a small pond. The southern slopes are
mostly covered with dense Tussac while the northern slopes
are rocky, and the vegetation consists of dry upland heath,
with Balsam-bog Bolax gummifera and exposed rock layers.
South Fur is a small island lying around 3 miles (5 km) off
the south coast of Steeple Jason. Just 0.6 miles (1 km) long
and 300 m wide, its highest point is only 18 m. Unusually, it
is composed mainly of large blue-grey dolerite boulders,
with a dense but low Tussac covering. It has not been
stocked with sheep or cattle.
North Fur lies north-east of Flat Jason and is difficult to
access due to steep cliffs formed from vertically bedded
rocks. It is heavily overgrown with dense and tall Tussac,
and has small amounts of Wild Celery Apium australe,
Stonecrop Crassula moschata and Swordgrass Carex trifida, but
it has never been stocked, probably because access is difficult.
‘Clarke’s Islet’ lies about 0.3 miles (0.5 km) off the
north-eastern coast of Grand Jason. It is a rugged low
island with many rock outcrops, patches of ‘black ground’
and open low Tussac, heavily used by Southern Sea Lions.
The Fridays are two small islands situated around 3 miles
(5 km) from the north-west coast of Flat Jason. Both are low
lying, and consist of large coastal rocky strike ridges with
Tussac between. On the larger of the two, this area gives
way in the centre to open peaty ground, which is the site of
a colony of Southern Giant Petrels. Southern Sea Lions use
both islands.

Key Biodiversity On Steeple Jason in October and November 1997, 36
species were noted, with 27 probably breeding, and 39
species were recorded on Grand Jason with 30 of them
almost certainly breeding. A total of 12 species, 11 probably
breeding, were found on Steeple Islet during a visit of only
90 minutes. Clarke’s Islet held only 10 species, almost all
breeding and including Cobb’s Wrens, Tussacbirds and
Canary-winged/Black-throated Finches. On Flat Jason, 32
species were seen, with 26 probably breeding. On Elephant
Jason, 33 species were noted, of which 30 were probably
breeding. Populations of Thin-billed Prions, Wilson’s
Storm-petrels, Grey-backed Storm-petrels, Rock Shags and
Imperial Shags warrant further investigation.
Endemic sub-species present are the Common Diving-petrel,
Black-crowned Night-heron, Upland Goose, Short-eared Owl,
Dark-faced Ground-tyrant, Falkland Grass Wren, Falkland
Thrush and the Long-tailed Meadowlark. The Falkland Pipit
is apparently absent from all islands in this extreme
western group.